principal

the educator who has executive authority for a school

“she sent unruly pupils to see the principal”

the major party to a financial transaction at a stock exchange; buys and sells for his own account

an actor who plays a principal role

capital as contrasted with the income derived from it

most important element

“the principal rivers of America”

any person involved in a criminal offense, regardless of whether the person profits from such involvement

the original amount of a debt on which interest is calculated